Improving Aerodynamics
01-03-2010, 07:40 AM
#76
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Have to aggree with the OP, I belive aerodynamics was his biggest MPG concern. Sure running 80 didn't help. But in my exp with my TT 32' Keystone BHDS, bumper pull, which dry weights right at 11K, anything over 65 & the truck is working hard regaurdless of head wind. Where as when pullin either my bumper pull or GN equipment trailers I can tun 70 to 75 without the "drag" affect. Even with 17K on the trailer not counting trailer weight. Have Reese dual cam sway control on TT & haven't exp any swap problems either. I usually get better MPG towing equip even though much heavier & faster speed than towing the TT.
Another example have hauled oversized concrete beams & parking deck panels, some up to 70' long on extenable flats, most always grossing over 90K. Pullin with a 379 Pete flat top with 550 CAT with a 13 denutted @ 75. Anyway back haul sometimes was "cans" sea containers. The cans "feel" heavier even though I'm only grossing 60k or so.
Another example have hauled oversized concrete beams & parking deck panels, some up to 70' long on extenable flats, most always grossing over 90K. Pullin with a 379 Pete flat top with 550 CAT with a 13 denutted @ 75. Anyway back haul sometimes was "cans" sea containers. The cans "feel" heavier even though I'm only grossing 60k or so.
01-03-2010, 11:56 AM
#77
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Let me start by writing that when I posted "you can't control" I meant to say that "one can't control", that is, any and all persons operating pickup trucks. Crash statistics for them are terrible, and only the foolish think themselves exempt.
Which while we are on that subject I really never had any problem with sway. In extreme cross wind situations I tell that the trailer is pushed from one side or the other but I have never had a problem with sway.
Again, I see this all the time. Just because it can't be felt from the steering wheel doesn't mean it isn't happening. By which I mean everything from small skips and jumps to the trailer leaning over from a side wind (against a very small amount of possible suspension travel) and the driver is unaware of it. I have seen tractor trailers with the rear tandems catching air under the tires on one side or another . . and the driver -- a professional -- can't "feel" it from the wheel. (But he sure heard the hollerin' on the CB).
Incipient sway is nearly always present. Inadequate weight transfer, cheap anti-sway kit, and changing road conditions present problems for tow rigs. Guessing at weights, failure to confirm proper W-D operation, improper trailer loading (Tongue Weight), etc, all add up. Have someone follow you with a video camera and record how well the units exhibit "unbroken linkage" (out of alignment with each other). It isn't just in lane changes. In trailering, the tail wags the dog. And a small trailer can upset even a "big" truck. Seen it often.
One thing any CDL driver can tell you is how limited, how few choices can be made, with an inherentlyunstable rig. As I see it, anything I can do to improve the margin with my TT is to the good. Road performance is everything, and it is a bit foolish to think that the bigger-the-better the TV is the "safer I'll be" (whistling in the dark).
AND it all pays off in directional stability, fewer steering corrections, and the "effect" on fuel economy is that it highlights effects such as the wind by having eliminated "noise" in the system.
Which while we are on that subject I really never had any problem with sway. In extreme cross wind situations I tell that the trailer is pushed from one side or the other but I have never had a problem with sway.
Again, I see this all the time. Just because it can't be felt from the steering wheel doesn't mean it isn't happening. By which I mean everything from small skips and jumps to the trailer leaning over from a side wind (against a very small amount of possible suspension travel) and the driver is unaware of it. I have seen tractor trailers with the rear tandems catching air under the tires on one side or another . . and the driver -- a professional -- can't "feel" it from the wheel. (But he sure heard the hollerin' on the CB).
Incipient sway is nearly always present. Inadequate weight transfer, cheap anti-sway kit, and changing road conditions present problems for tow rigs. Guessing at weights, failure to confirm proper W-D operation, improper trailer loading (Tongue Weight), etc, all add up. Have someone follow you with a video camera and record how well the units exhibit "unbroken linkage" (out of alignment with each other). It isn't just in lane changes. In trailering, the tail wags the dog. And a small trailer can upset even a "big" truck. Seen it often.
One thing any CDL driver can tell you is how limited, how few choices can be made, with an inherentlyunstable rig. As I see it, anything I can do to improve the margin with my TT is to the good. Road performance is everything, and it is a bit foolish to think that the bigger-the-better the TV is the "safer I'll be" (whistling in the dark).
AND it all pays off in directional stability, fewer steering corrections, and the "effect" on fuel economy is that it highlights effects such as the wind by having eliminated "noise" in the system.
.My first WD hitch was poorly matched by the salesman (Standard round WD hitch by reese). I whiteknuckled it the whole weekend and especially when a big rig would pass me and suck my trailer over the centre line!
With the Reese Dual cam high performance it is better but not gone, with 8' of trailer behind my trailer axles,a hitch can only do so much. At this point my trailer pulls very straight with minimal movement in X and passing semi's.
I have adjusted the hitch several times and feel it is as fine tuned as possible. The rest is up to my driving style and staying within the limits of my towing system!
01-03-2010, 01:32 PM
#79
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I agree as well on the aero dynamics point. I used to haul an in bed camper and pulled a 18ft trailer with my jeep on it, around 10K total.
Now I have the redneck toyhauler, 30ft GN with a 24ft 5th(minus suspension/axles) mounted on the front leaving just enough room on the back for the Jeep. It weighs in about 3K more than the old setup but feels the same. My guess is that the 5th wheel is set farther back and is a smaller "billboard" than the in bed camper was.
Steep hills I do notice the extra 3K but just cruising on the highway feels the same and bucking a head wind and passing semis is actually less noticeable, probably due a lot to the GN setup vs the bumper pull.
Now I have the redneck toyhauler, 30ft GN with a 24ft 5th(minus suspension/axles) mounted on the front leaving just enough room on the back for the Jeep. It weighs in about 3K more than the old setup but feels the same. My guess is that the 5th wheel is set farther back and is a smaller "billboard" than the in bed camper was.
Steep hills I do notice the extra 3K but just cruising on the highway feels the same and bucking a head wind and passing semis is actually less noticeable, probably due a lot to the GN setup vs the bumper pull.
01-04-2010, 04:24 PM
#80
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I'd go with the cab deflector for a gooseneck trailer.
01-04-2010, 06:38 PM
#82
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To be honest... its ALL wrong.
The truck wasn't made to pull a brick wall down the road at 75-80 miles an hour. The stock gear is too tall for the wind resistance encountered. The trailer has a flat front with extra ribs in the siding to create even more drag. The roof edges and the sides at the front and back are not rounded. If I remember from the beginning the belly is not enclosed smoothly. Some trailer manufacturers even use profiled roof sheeting and run it across the belly to create even more drag.
While there are a lot of trailers that use a shaped front to cut down on wind resistance but do very little at the rear which is where the most problems are. If you look at a jet aircraft most people think the "pointy end" is at the front and many refer to it this way even people in the biz, but in reality the real pointy end is at the rear. This holds true be it the fuselage, the wing or a flight control. I know it's not that practical to make the rear "pointy" but there is much that can be done and it was touched on in another post. Most changes would be required at the design stage but as was mentioned "airtabs" work wonders. They have been used on aircraft of all sizes for decades.
So the task is to tow this trailer at 75-80 mph. The engine needs to develop a ton more torque if it's going to push that gear to create the desired speed and airtabs on the rear sides of the trailer along with a smooth underbelly. Black coroplast (Sp) works for this.
The truck wasn't made to pull a brick wall down the road at 75-80 miles an hour. The stock gear is too tall for the wind resistance encountered. The trailer has a flat front with extra ribs in the siding to create even more drag. The roof edges and the sides at the front and back are not rounded. If I remember from the beginning the belly is not enclosed smoothly. Some trailer manufacturers even use profiled roof sheeting and run it across the belly to create even more drag. While there are a lot of trailers that use a shaped front to cut down on wind resistance but do very little at the rear which is where the most problems are. If you look at a jet aircraft most people think the "pointy end" is at the front and many refer to it this way even people in the biz, but in reality the real pointy end is at the rear. This holds true be it the fuselage, the wing or a flight control. I know it's not that practical to make the rear "pointy" but there is much that can be done and it was touched on in another post. Most changes would be required at the design stage but as was mentioned "airtabs" work wonders. They have been used on aircraft of all sizes for decades.
So the task is to tow this trailer at 75-80 mph. The engine needs to develop a ton more torque if it's going to push that gear to create the desired speed and airtabs on the rear sides of the trailer along with a smooth underbelly. Black coroplast (Sp) works for this.
01-04-2010, 10:32 PM
#83
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The only thing I can see you doing to improve the aerodynamics or air flow is to buy a full size truck topper like the one seen here.
A wing will not help you as the air will still drop behind the truck cab and hit the front of the trailer. In driving a semi I have learned that air will pass over a space of no bigger than around 4 feet. In other words, if the gap is larger than 4 feet, the air will start to enter the gap and hit the front of the trailer. This explains why a fifth wheel will get better fuel mileage than a travel trailer.
A wing will not help you as the air will still drop behind the truck cab and hit the front of the trailer. In driving a semi I have learned that air will pass over a space of no bigger than around 4 feet. In other words, if the gap is larger than 4 feet, the air will start to enter the gap and hit the front of the trailer. This explains why a fifth wheel will get better fuel mileage than a travel trailer.
01-10-2010, 12:12 PM
#84
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I'm confused you said your truck is an 05 your sig says 09. If you don't want to listen to people here go buy a cxt or something meant to tow with semi tires. Your truck simply does not have what it takes to do what you want. The reason it pulls better with a tail wind is just that. You have a tail wind! Now when you drive 80 which is dumb with a trailer on a bumper your only pushin say 55 or 60 mph worth of air. The point is you don't want to admit its a truck problem. I'm not saying it didn't do it stock. I'm just saying the truck is having issues. Your trailer is not that big.
01-10-2010, 05:25 PM
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I'm confused you said your truck is an 05 your sig says 09. If you don't want to listen to people here go buy a cxt or something meant to tow with semi tires. Your truck simply does not have what it takes to do what you want. The reason it pulls better with a tail wind is just that. You have a tail wind! Now when you drive 80 which is dumb with a trailer on a bumper your only pushin say 55 or 60 mph worth of air. The point is you don't want to admit its a truck problem. I'm not saying it didn't do it stock. I'm just saying the truck is having issues. Your trailer is not that big.
03-13-2010, 02:40 PM
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I see no mention of this air deflector,
Wingmaster Aerotravel Air-Deflector, the upslope wing.
At first glance these look like disturbing the airflow twice.
But just my 2 cents, I don't see many posts about air deflectors.
happy day
Wingmaster Aerotravel Air-Deflector, the upslope wing.
At first glance these look like disturbing the airflow twice.
But just my 2 cents, I don't see many posts about air deflectors.
happy day
03-15-2010, 10:09 AM
#87
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There have been several posts about air deflectors. I believe the genereal opinion is they do little to improve mileage. The primary result is: "It moves the bug line up on the Rig".
The best thing to improve milegae is drive 55, if you can live with that.
The best thing to improve milegae is drive 55, if you can live with that.
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